The probability of getting seriously ill or even dying from Covid-19 seems to be greater with the British variant B.1.1.7 than with other variants of Sars-CoV-2. That is what the results of a study by scientists from the British government suggest. “ The risk of hospitalization or death increases by about 40 to 60 percent,” said UK government epidemiologist and advisor Neil Ferguson to the New York Times. The so-called British variant thus seems not only more contagious, but also more dangerous.
Reasons for the increased risks in B.1.1.7 not clarified
This conclusion of the UK Government’s New and Emerging Respiratory Virus Threats Advisory Group (Nervtag) is based on an analysis of studies carried out in England, Wales and Scotland over the past few months after variant B.1.1.7 in the December 2020 was identified there for the first time.
B.1.1.7 is the result of mutations in the coronavirus: Since Sars-CoV-2 jumped to humans a little more than a year ago – we do not yet know where, how and from which animal species – several thousand variants have emerged. Researchers suspect that the British variant has advantages for the virus because it is more easily transmitted and apparently can also escape the antibodies: This increases the rate of infection and at the same time multiplies the number of people who can be infected. For this reason, it is to be expected that this variant will prevail. In the UK, it is already the dominant form of Sars-CoV-2.
Suspected two mutations
Suspected are two mutations in the spike protein (S protein) of the virus, these are the spines that give the coronavirus their name. One mutation, N501Y, replaced the amino acid asparagine (N) with tyrosine (Y). It is named after its position (501) on the RNA. The mutation is located on the spike protein and changes the shape and composition of the receptor surface of this protein.
Mutations at receptors are a problem because the antibodies formed by the immune system are designed to dock on this receptor surface in order to prevent the virion from docking again on body cells. Antibodies must be able to combine with the virus in order to render it harmless.
The other mutation that is acutely suspected of making the virus more dangerous is a so-called deletion, in which the amino acids are not replaced, but disappear entirely from the protein. In that case it is deletion 69 to 70 (69-70 or 69/70). This deletion is also located in the spike protein of Sars-CoV-2 and is also suspected of worsening the chances of antibodies to bind to the virus. If the antibodies are so ineffective, the viruses can multiply more easily and the individual viral load increases. This increased viral load is suspected to be a cause of the more severe courses and the increased mortality.
Different numbers on mortality and severe courses
As far as the likelihood of severe disease and mortality is concerned, the numbers of the individual scientific institutions in Great Britain fluctuate: According to the Nervtag report, the London School of Hygiene & Tropical Medicine has calculated an increased risk of disease and mortality by a factor of 1.58 , so by 58 percent. Imperial College London has a 36 percent higher death rate, scientists from the University of Exeter report a 70 percent higher mortality (factor 1.7), Public Health England (PHE) has an increased mortality rate of 65 percent. However, it seems certain that B.1.1.7 is rightly regarded as a “variant of concern”.